The present invention relates generally to measurements of tissues, optical elements and other structures, and, more particularly, to methods and systems for integrated ocular tomography and scanning laser ablation.
Corneal shape corrective surgeries are commonly used to treat myopia, hyperopia, astigmatism, and the like. Procedures employing an excimer laser include LASIK (Laser Assisted In-Situ Keratomileusis), PRK (Photo Refractive Keratectomy) and LASEK (Laser Subepithelial Keratomileusis). During LASIK, a suction ring is typically placed over sclera tissue (the white part of the eye) to hold the eye firmly. A surgeon first uses a microkeratome with an oscillating steel blade to make a partial cut through a front surface of a cornea. A microkeratome automatically passing across a cornea creates a thin flap of clear tissue on a front central part of an eye. A suction ring is then removed, and a flap is lifted back to sufficiently expose tissue for ablation with a laser. A laser is programmed to correct a desired amount of visual effect, and directs a laser beam. A rapid, continuous emission of laser pulses removes very small precise amounts of corneal tissue. After irrigation with saline solution, a corneal flap is folded back to adhere to its original position.
Precise measurement of corneal thickness may benefit LASIK and other corneal shape corrective surgeries. An ability to monitor corneal thickness during surgery is desirable because it may facilitate improved control over ablation and may lead to more precise reshaping of a cornea. Further, in situ surgical tomographic measurement of a cornea may prevent over and under correction with ablation and excessive thinning of a cornea having associated problems such as kera ectasia.
Problems encountered with techniques for measuring a tomography of a cornea have often included a length of time required to measure corneal thickness and difficulty sampling corneal thickness over an area of tissue, as opposed to sampling thickness at a single point of tissue. Previous surgical systems have typically measured a central point or small central region of a cornea during surgery. Measuring a single point or small central region is less than ideal because such measurements typically represent only a small portion of a total treated area.
In light of the above it would be desirable to provide improved systems and methods for measuring a thickness of a cornea during surgery.